How?
Penalty free release only kicks in when speeds are below what the ISP promised.
I would suggest that not allowing the user to be placed on an Openreach product that BT Wholesale says is available at a significantly higher speed is an unfair contract term.
There is no reason at all that the higher speed would be particularly unstable, or cause the speed obtained, whether sync or throughput, to fall below the promised one.
At worst it would require a deadlock letter and dispute resolution service, but it should be resolved much quicker than that if a high enough level is reached in Sky. (It shouldn't need to be particularly high either). I would expect the higher speed would be provided rather than the getout.
The only major reason the OP wouldn't want to go that way would be if services only available on Sky were regarded as essential, in which case basically the same route could be taken but simply pressing the speed request in the same way.
My broadband basic info/help site -
www.robertos.me.uk. Domains, site and mail hosting -
Tsohost.
Connection - Three 4G, tbb tests normally 35-45Mpbs down, 65Mbps off-peak, 9-24 up.
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If you never think of anything off the wall, you'll never think of anything original.